A New York Times report finds that prenatal genetic tests advertised for their accuracy are usually wrong when reporting results for rare genetic conditions.
This blog has detailed the over-stated accuracy of cell free DNA screening tests (commonly (& imprecisely) referred to as “NIPT” for “non-invasive prenatal testing”), even for the condition the New York Times articles recognizes such testing as revolutionary:
The tests initially looked for Down syndrome and worked very well.
Experts say it has revolutionized Down syndrome screening, significantly reducing the need for riskier tests.
most companies sell microdeletion testing as an optional add-on to the Down screening.
As is typical, “Down syndrome” quickly becomes shorthand for prenatal genetic testing; here, as the last quote shows, the authors shorten it even to “Down screening.”
However, for the rarer conditions cfDNA screening laboratories offer, the NY Times report found “positive results on those tests are incorrect about 85 percent of the time.” (emphasis added).
The article contains this helpful graphic:
The article shares how most women accepting this testing are seeking reassurance that their expectant child does not have a condition. Concerningly, the cfDNA screens only screen for a few microdeletions. “But there are hundreds of microdeletion syndromes, … meaning women shouldn’t take a negative result as proof their baby doesn’t have a genetic disorder.”
Similar to the critique offered by Robert Resta that these tests are providing reassurance for conditions so rare they should not be a concern, Mary Norton, an obstetrician and geneticist (written about here), is quoted as saying:
It’s a little like running mammograms on kids. The chance of breast cancer is so low, so why are you doing it? I think it’s purely a marketing thing.
In 2014, Beth Daley ran an expose reporting on the dire consequences that followed these screening tests. Only 6% of women pursued follow up testing with some of them opting to terminate based just off of a screen result, not a diagnostic test. The New York Times reports this is still happening:
Three geneticists recounted more recent examples in interviews with The Times. One described a case in which the follow-up testing revealed the fetus was healthy. But by the time the results came, the patient had already ended her pregnancy.
Similar to the lack of understanding demonstrated by the rapid rollout and overhyped marketing of cfDNA screens after they entered the marketplace in 2012, a decade later, many in the medical profession have not learned that these screening tests are just that: screening results and often wrong:
In interviews, 14 patients who got false positives said the experience was agonizing. They recalled frantically researching conditions they’d never heard of, followed by sleepless nights and days hiding their bulging bellies from friends. Eight said they never received any information about the possibility of a false positive, and five recalled that their doctor treated the test results as definitive.
Perhaps the medical professionals could be forgiven if the relative accuracy of cfDNA screens had not be the subject of multiple reports over the years, but relying solely on the marketing material they display from laboratories, these brochures still tout the screens accuracy:
The Times reviewed 17 patient and doctor brochures from eight of the testing companies, including Natera, Labcorp, Quest and smaller competitors. Ten of the brochures never mention that a false positive can happen. Only one mentioned how often each test gets positive results wrong.
The article details individual patient experiences, describing receiving the results as “agonizing.” One mother was phoned by her physician’s office with the micro-deletions screen result while en route to inform her parents she was pregnant with her first born wearing a “big brother” t-shirt.
Of course, the reason for the push to expand testing, regardless of its relative accuracy, is always the same: profit. As the article reports, prenatal genetic testing is already a billion dollar a year industry. If more insurers cover more microdeletion testing, the article reports one lab could generate $300 million in revenue each year.
And, so, money drives prenatal care–not accuracy or relevant information or patient care.
H/T to Amy Allison & Cassy Chesser for alerting me to this article via Facebook posts
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